To change the whole clamp assembly you will ned 1x2.5mm allen key and 1x4mm allen key. Undo the 2 4mm allen keys from the top of the clamp and remove the handle bar. Undo the 4x 2.5mm allen keys (2 each side) that go in sidewards in the stem just below the clamp, and pull out bottom section of the clamp. To refit place lower section and screw in the 4x2.5mm allen keys. Place the handle bar in position and fit the upper section of the clamp in and place and tighten the 4mm allen key bolts. Tip make sure the handle bar is in the correct position before tightening.